Although many reports have been published on the etiology of different types of leukemia, little is known about the risk factors associated with the myelodysplastic syndromes (MDS). Even less is known about the role that genetic susceptibility plays in the development of these syndromes. We propose to conduct a pilot case-control study of 180 MDS patients registered at the U. of Texas M. D. Anderson Cancer Center (MDACC) and 180 controls selected from friends and spouses who accompany patients to different MDACC clinics. Controls will be matched to the cases on age, sex, ethnicity, and state of residence. We propose to accrue 130 new cases and 130 controls to add to the 100 participants (50 cases and 50 controls) already collected. Epidemiological and demographic information obtained by personal interviews will be integrated with clinical, including cytogenetics, and genotypic markers. All participants will be genotyped for the following markers associated with activation and detoxification of chemical carcinogens (CYP2E1, CYP1A1, CYP1B1, GSTT1, GSTM1, GSTP1, NQO1, and MPO). This pilot study will provide insight in the understanding about the role that these genetic markers, along with epidemiological and clinical risk factors play in the identification of people at risk of MDS development. This study will provide data for a large multicenter study. The identification of risk factors associated with the development of MDS is an important health concern, as it could lead to the eventual prevention of this syndrome and consequent reduction in the incidence of AML.